2003 Trailblazer No air from front face vents

Air temperature and delivery are controlled via small actuators on the heating, ventilation & air conditioning (HVAC) box located behind the dashboard. These actuators operate doors inside the HVAC box in order to channel air through different passages to achieve the desired result. A "blend" door actuator can channel air through the heater core, around the heater core or a mix of these two to achieve the desired temperature. A "mode" door actuator can direct airflow to the ducts that lead to the defrost vent, front vent, floor vent or a mix between. When a vehicle has dual climate control (where driver and passenger sides of the vehicle can have different air temperatures) there can be multiple of actuators of each type which can make diagnosis difficult. The first step would be to retrieve diagnostic trouble codes (DTCs) from the HVAC Control Module using an advanced level scan tool; these codes help determine the location of the issue and if it's an electronic or mechanical failure. Electronic failures would include items such as HVAC control module failure, actuator circuit failure or actuator failure. Mechanical failures would include items such as actuator failure or internal HVAC box door failure. You can read more here: https://www.yourmechanic.com/article/what-components-of-the-heating-and-ac-system-are-most-likely-to-fail

Is your heater blower motor working on all speeds ? Are you get any air coming from the rear vents ?

I think your problem is the head unit that selects where the air comes out ie. Face, floor, defrost, or hi-level face and floor. If that's not working then it will not let you switch location that you want the air to come out.

Bob,if this is an automatic(climate control)type system,it could be a computer problem or electronic board problem.
I really wouldn't know where to start,except by phoning GM service manager and lay the problem before him.He may know EXACTLY what it is and tell you right over the phone.Sorry I'm no help here.(:^( don-ohio

yes it could be the blend door, could be broken, or the actuator, or could be the climate control too, if you know where the heater core is then you just found the blend door, goodluck. Thanks

You may have a blocked vent system.

If I am reading correctly you are hearing the vent doors moving to redirect the airflow to the vents you choose. This is normal and can be more noticeable if the blower fan is on, putting air pressure against the doors.

If it is a mechanical switch that you turn this system works by vacume it could be the vacume supply hose coming from the intake manifold is either off or broken.

You could also have disconnected it by mistake when you changed the climate control. Good luck

disconnect the battery and try again to re sync the two sides, this is a common problem on all dual climate GM cars, if you can't get them to resync then you will need to replace the climate control head..

maybe recharge your ac